Transparent composite materials are known for use in vehicle and other applications requiring light transmission or visual transparency. Such transparent composite materials include windows or other transparent materials useful for light transmission there through, particularly in rugged environments and in locations requiring ballistic resistance. Such reinforcement further provides the window or transparent device resistance to cracking or breakage.
Transparent composite materials typically include a reinforcing fiber in a polymeric matrix. In order to render the composite material transparent, both the matrix material and the reinforcing fiber are fabricated from a transparent material. The materials are typically selected to include the same optical properties, thus minimizing distortion.
The geometry of reinforcing fibers also affects the distortion imparted to the light passing through the transparent device. For example, round fibers (i.e., fibers having circular cross-section) provide prismatic or other optical light refractive effects that provide overall distortion of the light passing through the transparent device.
These transparent composite materials are also required to withstand high impacts and structural loads, and thus are required to have high strength and environmental durability. Environmental durability includes resistance to moisture, corrosion, ultra-violet (UV) light, solvents and other similar deleterious materials and conditions. The environmental durability of the composite is dependent upon the durability of both the matrix material and the reinforcing fibers. The term “durability” is intended to mean “environmental durability” for the remainder of this disclosure.
The reinforcing fibers are selected based on the required optical, strength, durability and cost requirements of the composite. However, often to meet optical, strength, and cost requirements, a fiber material selected has a less than desirable environmental resistance or durability, and in particular, resistance to chemical attack.
What is needed is a fiber reinforcing material having improved durability at a reduced cost.